const uint8_t *SIGNALS[] = {
    sinewave
    ...
};

void static inline Signal_OUT(const uint8_t *signal, uint8_t ad2, uint8_t ad1, uint8_t ad0)
{
    asm volatile(
        "eor r18, r18   ;r18<-0"    "\n\t"
        "eor r19, r19   ;r19<-0"    "\n\t"
        "1:"                        "\n\t"
        "add r18, %0    ;1 cycle"           "\n\t"
        "adc r19, %1    ;1 cycle"           "\n\t"
        "adc %A3, %2    ;1 cycle"           "\n\t"
        "lpm            ;3 cycles"  "\n\t"
        "out %4, r0     ;1 cycle"   "\n\t"
        "sbis %5, 2     ;1 cycle if no skip" "\n\t"
        "rjmp 1b        ;2 cycles. Total 10 cycles" "\n\t"
        :
        :"r" (ad0),"r" (ad1),"r" (ad2),"e" (signal),"I" (_SFR_IO_ADDR(PORTA)), "I" (_SFR_IO_ADDR(PORTD))
        :"r18", "r19"
    );
}

Signal_OUT(SIGNALS[SG.mode], ...);